Plains

Dispatch

Tap target creature.
Metalcraft — If you control three or more artifacts, exile that creature.

Cathar's Shield

Equipped creature gets +0/+3 and has vigilance.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Danitha Capashen, Paragon

First strike, vigilance, lifelink
Aura and Equipment spells you cast cost {1} less to cast.

Auriok Sunchaser

Metalcraft — As long as you control three or more artifacts, Auriok Sunchaser gets +2/+2 and has flying.

Spiraling Duelist

Metalcraft — Spiraling Duelist has double strike as long as you control three or more artifacts.

Cage of Hands

Enchant creature
Enchanted creature can't attack or block.
{1}{W}: Return Cage of Hands to its owner's hand.

Armored Transport

Prevent all combat damage that would be dealt to Armored Transport by creatures blocking it.

Ironclad Slayer

When Ironclad Slayer enters, you may return target Aura or Equipment card from your graveyard to your hand.

Militant Inquisitor

Militant Inquisitor gets +1/+0 for each Equipment you control.

Tajic, Blade of the Legion

Indestructible
Battalion — Whenever Tajic, Blade of the Legion and at least two other creatures attack, Tajic gets +5/+5 until end of turn.

Accorder's Shield

Equipped creature gets +0/+3 and has vigilance. (Attacking doesn't cause it to tap.)
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Auriok Edgewright

Metalcraft — Auriok Edgewright has double strike as long as you control three or more artifacts.

Disenchant

Mountain

Ardent Recruit

Metalcraft — Ardent Recruit gets +2/+2 as long as you control three or more artifacts.

Kor Duelist

As long as Kor Duelist is equipped, it has double strike. (It deals both first-strike and regular combat damage.)